WO 06130085 describes in general a positioning device and in particular a device, which is mainly used when positioning of a disc implant in combination with separating of vertebrae. The positioning of the disc implant results in accurate replacement of the disc that causes pain, reinstating the distance between the vertebrae and reinstating movability between them.
In particular, WO 06130085 discloses distance means that carry engagement means for the engagement with two vertebrae at a distance from each other. Said distance means are arranged such that they are capable of changing the degree of separation of said vertebrae when the engagement means are in engagement therewith. The possibility of spanning apart the vertebrae makes it possible, i.a. to freely remove the old disc.
When two distance means, carrying the engagement means, are arranged in parallel, handling of a holder and a prosthesis/an implant carried thereby takes place between these distance means.
In WO 06130085, the engagement means are connected to the distance means in friction joints such that the engagement means are movably fastened to the distance devices in order to avoid excess breaking forces in connection with separating vertebrae.
WO 9002527 concerns a distractor having parallel coupled first and second adjustment means for maneuvering engagement screws. This distractor gives limited possibilities for controlling the displacement of bones and is impractical for use in a real life situation.